In many types of subsea production operations, hydrocarbon fluids and/or other process fluids are flowed through process flow lines. The flowing process fluids may be multiphase fluids containing various types of liquid and gas phases. For example, a process fluid may contain a gas-oil-water mixture. Additionally, the water phase may contain salt water and mixtures of water and water soluble chemicals. However, determining properties related to individual constituents of the multiphase fluids can be difficult while the phases remain mixed.